It has been developed that cuts off an audio signal with respect to a predetermined frequency band using a digital filter and inserts, with respect to the predetermined frequency band, an orthogonal frequency division multiplexing (OFDM) signal commonly used for wireless communication, or changes a phase in the frequency-dimension through a modified complex lapped transform (MCLT) for acoustic communication.
Above measures are to insert a signal into audio signal that may not be recognized by a human, so as to maintain the utility of an audio signal and enable acoustic communication.
However, conventional acoustic communication may have deterioration of performance due to ambient noise or a characteristic associated with transmission via air and thus, the conventional acoustic communication may have difficulty in performing reliable transmission of information. Particularly, when a single subcarrier is used for transmitting single data in the acoustic communication that is significantly affected by a change in ambient environment, the bit error rate (BER) of data increases and communication performance may not be guaranteed.